Prostate cancer is the most common non-skin cancer in United States men. Despite recent advances, prostate cancer mortality still remains high due to the emergence of therapy-resistant cancer cells that metastasize. This lack of effective therapies against metastatic cancer exists, at least in part, because of lack of drug screening platforms that address the unique nature of metastastatic prostate cancer cells and their microenvironment. Recently, our collaborators have found that prostate cancer (PCa) cells act as molecular parasites as they metastasize to bone and harvest resources from the hematopoietic stem cell (HSC) niche environment where they stay dormant and resistant to conventional anti-cancer drugs. If the dormant metastasized PCa cells that parasitize the HSC niche could be recreated in vitro, they would serve as ideal platforms to screen specifically for anti-metastatic PCa drugs. We have recently shown that 3D co-culture spheroids can mimic the PCa cell parasitized HSC niche thereby maintaining PCa cells in a physiological, more quiescent state. What is required to take advantage of the metastatic PCa microtissue engineering capability we have acquired for drug screening applications is to develop a high throughput format of these types of co-culture spheroids. Towards this end, this Phase I STTR proposal will: Aim 1: Validate a 384 array hanging drop plate system for preparation of the co-culture spheroids. This is a major focus of 3-D Biomatrix, LLC. We have already modified our published platform (Tung et al. 2011) to: enhance droplet stability, facilitate pipette tip insertin, mitigate evaporation, and preserve sterility during optical analysis (Figure 1A). We will perform high throughput performance validations for fluorescence, transmitted light, and bioluminescence assays (Z'- factor), and further refine the design as necessary. Aim 2: Create arrays of microengineered 3D tissues of bone metastasized PCa in the quiescent state. This will be the focus of the Takayama lab at the University of Michigan. To develop procedures to utilize the 384 array hanging drop plate to form co-culture spheroids of PCa cells, marrow stromal cells (MSCs), and human bone marrow endothelial cells (HBMECs) similar to those prepared previously in low throughput microfluidic devices. We will also confirm quiescence of the PCa cells in these co-culture spheroids. The biological hypothesis that motivates this study is: We can treat metastatic PCa better by developing drugs that specifically target dormant metastatic PCa cells that are parasitizing the HSC niche. PHS 398 (Rev. 11/07) Page 1 PUBLIC HEALTH RELEVANCE: Prostate cancer cells act as molecular parasites as they metastasize to bone and harvest resources from the hematopoietic stem cell niche environment where they stay dormant and resistant to conventional anti-cancer drugs. This proposal will develop technology to recreate this metastatic prostate cancer microenvironment in a high throughput drug screening compatible format. This will enable development of better drugs against metastatic prostate cancer that specifically targets the conventionally difficult-to-target dormant metastatic PCa cells that are parasitizing the HSC niche. PHS 398 (Rev. 11/07) Page 1.